Classic and contemporary studies - Biological Psychology Flashcards
What was the aim of Raine’s study?
Wanted to use brain scanning technology to identify brain impairments in people charged with murder who had pleaded not guilty by reason of insanity
What was the procedure of Raine’s study?
-Experimental group was 39 men and 2 women charged with murder in California
-Murderers were matched on sex, age and ethnicity with a control group of non-murderers.
-Each participant underwent a PET scan on their brain. Each then completed a continuous performance task which involved identifiying targets on a screen and pressing a button during a 32 minute period. PET scan was conducted immediately after 32 minute period and took 10 images
What were the findings of Raine’s study?
Cortical regions - murderers had significantly low glucose metabolism. Murderers showed higher metabolism than controls in the occipital lobe, a brain area not linked to violence
Subcortical regions - murderers had low glucose metabolism. Murderers had greater activity in the right amygdala, the right temporal lobe and right thalamus
What was the conclusion of Raine’s study?
-Findings showed murderers pleading “not guilty by insanity” have different brain activity from people who aren’t violent offenders. The murderers had impaired functions in areas of the brain previously identified as involved with violent behaviour
-Researchers concluded dysfunction of a single brain area cannot explain violent behaviour
-We should be cautious in interpreting the findings as there are other brain areas involved in violence that can’t be measured
Evaluation of Raine study
-Strength is high degree of control. Standardised procedures were use to control other variables. This means the study had high internal validity as potentially confounding variables were controlled. However, the participants were randomly allocated to the experimental or control groups so matching wasn’t thorough which could have confounded results
-Weakness is PET scanning technique may have given misleading results. The carthomeatal line made it hard to locate precisely the different brain areas under study. This is a limitation because it reduces internal validity of the study and casts doubt on accuracy of findings
-Another strength is to be cautious about biological evidence. Raine argues findings don’t show treatment would be justified because the brain structures are only in partial explanation. Therefore, this research is important in identifying what biological evidence does and doesn’t tell us
What was the aim of Bredgens study?
Bredgen investigated aggression in M2 and D2 twins to discuss the extent which social/physical aggression are explained by genetic and environmental influences and whether the overlap between physical/social aggression is explained by direct effect of one type of aggression on another
What was the procedure of Bredgens study?
-234 twins selected from longitudinal QNTS. The QNTS collected data from twins regularly from 5-72 months
-Teacher ratings - kindergarten teachers rated social/physical aggression of each child on a three point scale in response to aggression
-Peer ratings - each classmate was given a book of photographs of every classmate and were asked to nominate 3 children who best described the behaviour. There were two descriptions for social aggression: “tells mean secrets about another child” and two descriptions for physical aggression “gets into fights”
What were the findings of Bredgens study?
-Only 20% of teacher findings compared to 23% of peer findings was explained by genetic factors
-Physical aggression was explained by non-shared environmental factors partly and social aggression was explained by non-shared environmental factors mostly
-High physical aggression led to high social aggression but not vice versa
What was the conclusion of Bredgens study?
-Data suggests genetic characteristics predispose some children to aggressive behaviour in general
-The directional relationship between social and physical aggression is explained by developmental processes
Evaluation of Bredgens study
-Strength of study is researchers used ratings of aggression from two sources. The two sets of teachers and peer ratings were essentially the same, which provides some reassurances that they are valid and reliable measures of aggressive behaviour
-Weakness is they are based on equal environments assumption. This states M2 and D2 twins experience similar treatment to the same extent. However, this assumption may be wrong. There are many ways in which this assumption is violated, seriously undermining the validity of study method. However, many of the ways in which M2 similarity occurs are irrelevant to the behaviour being investigated. Derks et al (2006) conducted a study of aggression in adolescent twins and used statistical methods to show the assumption wasn’t violated. Therefore the assumption is reasonably valid.
-Strength is this study could lead to effective interventions to reduce aggression. Given the progression of aggressive behaviour highlighted in the study, interventions should focus on preventing physical aggression in early years. Intervention based on this research could disrupt the transformation of physical to social aggression, ultimately reducing both types
